GHSA-75vm-6w67-gwvp CVE-2026-55076 GO-2026-5907

Coder's OIDC email_verified type coercion bypass enables account takeover via unverified email linking

High Go

Severity: 7.4 / 10; High · CVSS 3.1
Exploit chance (EPSS): 0.61%; Chance of exploitation in the next 30 days. Higher than 49.23% of scored vulnerabilities.
Known exploited: No; Not in CISA's catalog
Weakness: CWE-287 Improper Authentication; CWE-704 Incorrect Type Conversion or Cast
Fix: 2.34.2; Upgrade github.com/coder/coder/v2 to this version or later

Description

Summary

Coder's OIDC callback checked email_verified with a direct Go bool type assertion. When an IdP returned the claim as a non-boolean (for example the string "false") or omitted it, the assertion failed open and the email was treated as verified. Combined with an unconditional email-based account fallback, this enabled account takeover.

Impact

An attacker who registered a victim's email at a compatible IdP without verifying it could log in via OIDC and be matched to the victim's existing Coder account, receiving a session for that account. No prior authentication to Coder was required and the result was full account takeover.

Patches

The fix coerces email_verified across bool, string and numeric types (fail-closed) and blocks the email fallback when the matched user already has a different linked IdP subject.

The fix was backported to all supported release lines:

Release line	Patched version
2.34	v2.34.2
2.33	v2.33.8
2.32	v2.32.7
2.29 (ESR)	v2.29.17

Workarounds

Ensure the IdP returns email_verified as a native JSON boolean. The email-fallback linking issue has no configuration workaround; upgrading is required.

Resources

Fix: #25712, #25713

Credits

Coder would like to thank Anthropic's Security Team (ANT-2026-22444) for independently disclosing this issue!

Affected versions

Go

Package	Vulnerable	Fixed in
github.com/coder/coder	`all versions`	No fix yet
github.com/coder/coder/v2	`>= 2.34.0, < 2.34.2`	`2.34.2`
github.com/coder/coder/v2	`>= 2.33.0, < 2.33.8`	`2.33.8`
github.com/coder/coder/v2	`>= 2.30.0, < 2.32.7`	`2.32.7`
github.com/coder/coder/v2	`< 2.29.17`	`2.29.17`
github.com/coder/coder/v2	`< 2.29.17` `>= 2.30.0, < 2.32.7` `>= 2.33.0, < 2.33.8` `>= 2.34.0, < 2.34.2`	`2.29.17` `2.32.7` `2.33.8` `2.34.2`

How to fix

Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.

github.com/coder/coder/v2 Go → `2.34.2`

go

go get github.com/coder/coder/v2@v2.34.2 && go mod tidy

Severity breakdown

CVSS 3.1 7.4

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

Attack vector: Network
Attack complexity: High
Privileges required: None
User interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: High
Availability: None

Weakness

CWE-287: Improper Authentication

When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.

How to prevent it

Architecture and Design: Use an authentication framework or library such as the OWASP ESAPI Authentication feature.

CWE-704: Incorrect Type Conversion or Cast

The product does not correctly convert an object, resource, or structure from one type to a different type.

References

Fixes and patches

Packages

github.com/coder/coder

Timeline

Jul 6, 2026 Published
Jul 8, 2026 Last updated by the source
Oct 31, 2026 Latest EPSS score

Advisory	Severity	Why it's related
GHSA-h58c-xccx-75m3 Coder: Stored HTML injection via unescaped ApplicationName and LogoURL appearance settings	Medium	Also affects github.com/coder/coder
GHSA-8fxq-53rx-ph5f Coder: Login endpoint user enumeration via timing-defense placeholder in password comparison	Medium	Also affects github.com/coder/coder
GHSA-qrwj-vh9x-gw5v Coder's workspace agent API insecure redirect handling allowed cross-agent file read and write	High	Also affects github.com/coder/coder
GHSA-5wg6-jmq2-53pw Coder's workspace app CORS origin check can be bypassed via UUID-based subdomain spoofing	Medium	Also affects github.com/coder/coder
GHSA-7qw2-f75v-62f7 Coder vulnerable to stored HTML injection via workspace agent logs in AgentLogLine component	Medium	Also affects github.com/coder/coder
GHSA-84rm-42xw-mx52 Coder's AI Bridge Proxy skips TLS certificate verification in default configuration	High	Also affects github.com/coder/coder
GHSA-wqxv-w64v-5wh6 Suspended Coder users retain access to AI Bridge LLM proxy endpoints	Medium	Also affects github.com/coder/coder
GHSA-f5vp-w269-392g Coder vulnerable to denial of service via unbounded request body in AI Bridge provider endpoints	Medium	Also affects github.com/coder/coder

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